Circuit substrate and circuit substrate manufacturing method

Abstract

A circuit substrate includes protruding terminals and has a structure that ensures an excellent connection with an electronic component, such as an IC. The circuit substrate on which an IC is to be mounted includes terminals that are to be electrically connected to solder bumps located on the IC. The terminals protrude from the mounting surface of a substrate body on which the IC is to be mounted. The sectional area of the top surface of each of the terminals is about 1.2 times the sectional area of each of the terminals on the mounting surface.

Description

BACKGROUND OF THE INVENTION[0001]1. Field of the Invention[0002]The present invention relates to a circuit substrate and a circuit substrate manufacturing method and, in particular, to a circuit substrate on which an electronic component is to be mounted and a circuit substrate manufacturing method.[0003]2. Description of the Related Art[0004]Conventionally, when mounting an electronic component, such as an IC, on a circuit substrate, a mounting method as described below has been performed. Flat electrode pads are formed in an array on the main surface of the circuit substrate. On the other hand, solder bumps are formed in an array on the main surface of the IC. The IC is placed on the circuit substrate in such a manner that the solder bumps are positioned on the electrode pads, and then reflow is performed. Thus, the solder bumps are molten and then the solder bumps and electrode pads are fixed to each other. In this way, the IC is mounted on the circuit substrate.[0005]However, wh...

AI Technical Summary

Benefits of technology

[0011]Accordingly, preferred embodiments of the present invention provide a circuit substrate that includes protruding terminals and prevents a poor connection with an electronic component, such as an IC, and also provide a circuit substrate manufacturing method.

[0013]According to a preferred embodiment of the present invention, the top surface of the terminal is wider than the section of the terminal located at the mounting surface of the substrate body. For this reason, a loss of contact between the terminal and solder bump due to shock within the period from alignment between the terminal and solder bump to performance of reflow is prevented. As a result, a poor connection between the electronic component and circuit substrate is prevented.

[0016]A preferred embodiment of the present invention provides a circuit substrate on which an electronic component is to be mounted. The circuit substrate includes a substrate body and a terminal to be electrically connected to a bump on the electronic component. The terminal is arranged to protrude from a mounting surface of the substrate body on which the electronic component is to be mounted. A sectional area of a section of the terminal that is parallel or substantially parallel with the mounting surface increases from a section at the mounting surface of the substrate body to a top surface of the terminal and a change rate of the sectional area of the terminal at an area of the top surface is larger than a change rate of the sectional area of the section of the terminal at the mounting surface of the substrate body.

[0017]According to another preferred embodiment of the present invention, a method for manufacturing a circuit substrate on which an electronic component is to be mounted and that includes a terminal to be electrically connected to a bump located on the electronic component includes the steps of forming, on a first sheet, a mask layer softer than the first sheet; making a through hole on the mask layer; filling the through hole with a conductor; obtaining a multilayer body by crimping a plurality of second sheets, the first sheet, and the mask layer onto one another in such a manner that the mask layer is the uppermost layer; and eliminating the mask layer from the multilayer body.

[0024]According to a preferred embodiment of the present invention, the top surface of the terminal is wider than the section of the terminal on the mounting surface of the substrate body. Therefore, the electronic component and circuit substrate are prevented from making a poor connection with each other.

Problems solved by technology

However, when performing the above-mentioned mounting method, for example, the circuit substrate may become distorted by heat, since the thermal expansion coefficient of the circuit substrate is different from that of the IC.

Thus, the circuit substrate and IC may make a poor connection with each other.

However, the above-mentioned semiconductor element substrates have a problem in that it is difficult to mount the IC on the circuit substrate accurately.

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